Final answer:
Thiamine (Vitamin B1) deficiency results in polyneuritis, edema, and Wernicke's encephalopathy, particularly in alcoholics, while Vitamin B12 deficiency typically causes megaloblastic anemia and neurological disturbances. Both deficiencies can affect the nervous system, but they present with distinctly different symptoms and complications.
Step-by-step explanation:
Thiamine deficiency, also known as Beri-Beri, presents with symptoms such as polyneuritis, edema, cardiovascular changes, weakness, and gastrointestinal disorders. A specific manifestation in alcoholics is Wernicke's encephalopathy. In contrast, Vitamin B12 deficiency commonly leads to megaloblastic anemia and can cause neurological disturbances, but does not present with the same cardiovascular or edema issues characteristic of thiamine deficiency. Thiamine is crucial for carbohydrate metabolism and neural function, and its deficiency disrupts the brain's utilization of glucose, leading to nervous system impairments. B12 is important for DNA synthesis and red blood cell formation, and its deficiency may result in anemia and nerve damage. Daily intake of thiamine is essential due to its water-soluble nature and limited storage in the body. B12, on the other hand, can be stored in the liver for years, but its deficiency can still arise from factors such as poor diet or malabsorption.